Started working on sodium_ utility functions

multiplatform-crypto-libsodium-bindings/src/commonMain/kotlin/com.ionspin.kotlin.crypto/util/LibsodiumUtil.kt

@@ -5,6 +5,19 @@ package com.ionspin.kotlin.crypto.util
  * ugljesa.jovanovic@ionspin.com
  * on 31-Aug-2020
  */
-//expect object LibsodiumUtil {
-//
-//}
+expect object LibsodiumUtil {
+
+    fun memcmp(first: UByteArray, second: UByteArray) : Boolean
+    fun memzero(target: UByteArray)
+
+    fun pad(unpaddedData : UByteArray, blocksize: Int) : UByteArray
+    fun unpad(paddedData: UByteArray, blocksize: Int) : UByteArray
+
+    fun toBase64(data: UByteArray) : String
+    fun toHex(data: UByteArray) : String
+    fun toString(data : UByteArray) : String
+
+    fun fromBase64(data: String) : UByteArray
+    fun fromHex(data: String) : UByteArray
+    fun fromString(data: String) : UByteArray
+}